Terfenol-D

Two laminated pieces of Terfenol-D, one containing a drilled hole.

Terfenol-D is an alloy comprised of Terbium, Dysprosium and Iron. Terfenol-D has the largest room temperature magnetostriction of any known material. Terfenol-D is a solid-state material capable of converting energy from one form to another. In the case of electrical-to-mechanical conversion, the magnetostriction of the Terfenol-D generates strains 100 times greater than traditional magnetostrictives, and 2-5 times greater than traditional piezoceramics. The material has a high Curie temperature (380°C), which enables magnetostrictive performance greater than 1000 ppm from room temperature to 200°C. Adjustments in alloy composition can extend this range down to cryogenic temperatures.

The name Terfenol originated from the metallic elements, Terbium (TER) and Iron (FE); and the discovering organization, Naval Ordnance Laboratory (NOL). Dysprosium (-D) was added as an alloying addition later to reduce the magnetic fields required to induce the magnetostrictive response. NOL, now known as the Naval Surface Warfare Center – Carderock Division (NSWCCD) developed Terfenol-D for high power sonar offering greater bandwidth and reliability over legacy technologies. TdVib holds key patents and licenses for many Terfenol-D applications, including exclusive worldwide licenses to manufacture several types of Terfenol-D materials. TdVib is the world’s leading supplier of Terfenol-D materials and products. Additionally, TdVib provides assistance with the design and manufacturing of Terfenol-D driven products.

Physical Properties

Terfenol-D’s physical properties are provided in the table. Terfenol-D exhibits a large magnetostrictive and magnetic flux density response versus applied magnetic field over a large range of compressive stresses. The following graphs are representative of Terfenol-D produced by TdVib.

In addition, TdVib can tailor the Terfenol-D composition to allow for a wider operating temperature range. By adjusting the Tb:Dy ratio large magnetostriction values can be achieved at temperatures as low as -200°C and as high as 200°C.